Definition: You are given a question on nutrition. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: Which of the following factors inhibits non-haem iron bioavailability the most?

(A)Phytic acid (B)Citric acid (C)Vegetable protein (D)Calcium

A